We've been discussing switching from woff fonts to SVG for site icons. Some of the problems we have with web fonts (woff etc.) are:

• Line height and rounding issues look slightly 'off' (spinner icon seems a bit wonky, vertical alignment is off by a pixel or two, etc.)
• Editing web fonts relies on external service and rebuilding each time we add an icon
• Using unicode addresses for all glyphs is impossible (*).

* To maximize design flexibility we have included multiple versions of, say, a map icon. We cannot give both of them the same unicode address. To overcome this we'd need multiple fonts.
Also, sometimes it's impossible to find a unicode address for the glyph you want to use - so you use a private use area address, or you abuse an orthography glyph because it looks similar to your icon/glyph - see hamburger menu.

So, to explore the implications of making this switch I built a test file that uses 4 methods of doing this, along with my recommendations.